On Saturday 27 May 2006 10:00, Con Kolivas wrote:> On Saturday 27 May 2006 09:54, Folkert van Heusden wrote:> > > > These are nice-looking numbers, but one wonders. If optimising> > > > readahead makes this much difference to postgresql performance then> > > > postgresql should be doing the readahead itself, rather than relying> > > > upon the kernel's ability to guess what the application will be doing> > > > in the future. Because surely the database can do a better job of> > > > that than the kernel.> > >> > > With that argument we should remove all readahead from the kernel?> > > Because it's already trying to guess what the application will do.> > > I suspect it's better to have good readahead code in the kernel> > > than in a zillion application.> >> > Maybe a pluggable read-ahead system could be implemented.>> Pluggable anything is unpopular with Linus and other maintainers. See> pluggable cpu scheduler and pluggable page replacement policy (vm)> patchsets.

Sorry I should have been clearer. The belief is that certain infrastructure components do not benefit from a pluggable framework, and readeahead probably comes under that description. It's not like Linus was implying we should only have one filesystem for example, since filesystems are afterall pluggable features.